The invention relates to a suction-throttled pump comprising at least one displacement body for the delivery of a medium in accordance with the preamble of claim 1.
Suction-throttled pumps are known. They are used in motor vehicles, for example, and operated at varying speeds. The flow of medium required by the pump consumer is limited. At high pump speeds, the delivery rate of the medium would be too high. Therefore, a throttle valve, also referred to as a suction control valve, is provided in the suction region of the pump, i.e. between the pump and a reservoir or tank, and limits the quantity of medium sucked in. If pumps of this type are used in connection with a liquid medium, for example hydraulic oil, the static pressure in the suction region of the pump can drop below atmospheric pressure, with the result that foam forms. The dynamic properties of the pump are permanently impaired by the foam-containing oil. Furthermore, a pump displacer, which delivers the medium, is not uniformly filled on account of the foam, resulting in a non-uniform delivery rate. Moreover, the operating noises of the pump increase considerably.